. cl as s - ph ] 2 8 A ug 2 00 3 Restricted equivalence of paired epsilon – negative and mu – negative layers to a negative phase – velocity material ( alias left – handed material )

The time–harmonic electromagnetic responses of (a) a bilayer made of an epsilon–negative layer and a mu–negative layer, and (b) a single layer of a negative phase– velocity material are compared. Provided all layers are electrically thin, a restricted equivalence between (a) and (b) exists. The restricted equivalence depends on the linear polarization state and the transverse wavenumber. Implications for perfect lenses and parallel–plate waveguides are considered.